Biochemical sensors with structured and porous silicon capacitors

Chemical sensors with structured and porous semiconductor/insulator capacitors have been developed. The sensors have been prepared using standard techniques of semiconductor processing, i.e. by means of an anisotropic and anodic etching process, respectively. Both sensor types exhibit a high, near-Nernstian pH sensitivity of about 54 mV per pH decade. Due to the enlargement of the active sensor area, the measured capacitance values increase up to a factor of 30. These structured and porous electrolyte–insulator–semiconductor (EIS) sensor substrates are suitable as transducer material for biosensors which has been demonstrated by depositing the enzyme penicillinase through physical adsorption onto the respective pH-sensitive EIS capacitors.